Evidence-based On-call

Pulmonary embolism

Investigations

d-dimer ^a

in clinically low-risk cases ^a

Use a whole-blood agglutination test ^a

Why?

A negative d-dimer rules out a PE in low-risk cases - post-test probability 0.2%

A negative d-dimer can rule out PE in low-risk cases

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR- (95% CI)	Post-test Probability
ranked on clinical diagnosis rule as low risk for PE ^a (pre-test probability: 9.5%)	pulmonary embolism (V/Q scan, pulmonary angiogram, ultrasound, follow-up)	d-dimer negative (whole blood agglutination)	0.023 (0.0032 to 0.16)	0.2%